This invention relates to a control circuit for permanent magnet or constant excitation direct current motors, particularly for washing machines, the control circuit comprising reference means for providing a reference signal (V.sub.R) indicative of a desired motor speed, measuring means for measuring the actual motor speed, modulator means (28) receiving a control signal (V.sub.3) in order to control at least one static switch (5) in series with the motor (1), and control signal generating means for generating the control signal in dependence on the difference between the motor speed measured and the desired motor speed.
A circuit of the aforesaid type is known from the German patent application DE No. 3221093 which describes a circuit for regulating the rotational speed of a DC motor. In the known circuit, a tachometer dynamo is fixed onto the shaft of said motor, said dynamo generating a signal which is proportional to the motor rotational speed. This speed signal is fed to an electronic circuit which acts on the motor to regulate its speed, when required.
In the case of tachometer dynamos, their cost is relatively high and their installation is often laborious and costly.